Pita Tori Biddle's hand was shaking when he stood to speak in the whare Ruamoko at Waiaua Marae this week.

The 67-year-old wore a blue suit with a matching hat that he removed long before he rose in the dark house.

It was after lunch on a Wednesday at this place on a little hill outside of Opotiki where people left their shoes on the white-washed porch.

Dating to 1899 it felt old, with its glass stained windows and memories, and pictures of those who have died hanging benignly on the walls.

Mr Biddle was here to talk about his tupuna Te Whakatohea chief Mokomoko, who was hanged on the gallows in Auckland on May 17, 1866, for the murder of missionary Carl Sylvius Volkner.

Later, he'd describe the morning like this. "Well, I was scared. This is the first time I've been on a table like this ... I didn't know where to start but I just let it go."

He took a breath, looked down at his iPad where his notes were. He might have glimpsed song words that prefaced his remarks, written by Mokomoko.

"Tangohia te taura i taku kaki, kia waiata au i taku waiata."

The imagery it invokes is stark - a rope around Mokomoko's throat. His composition asks for it to be removed so he can sing his song. These days it's used as a whakatauki, a saying or reminder used by the chief's descendants to have the strength to tell the truth.

Mr Biddle's hand and voice steadied and he launched into a submission on behalf of his whanau's leadership group to the Maori Affairs select committee, in support of the Mokomoko (Restoration of Character, Mana and Reputation) Bill.

In Maori he told MPs of the shame endured by Mokomoko who maintained his innocence or any involvement in the crime.

"It was during the ensuing years of his conviction - the earlier generations, that the ripple effect on the whanau was felt with the most extreme prejudice; resentment, anger, even hatred.

"This prejudice had such a profound effect on our whanau that many living today still feel and carry the shame that was bestowed upon the earlier generations."

A pardon was granted in 1992. It was linked to 1988 legislation that, while not directly about the crime, pardoned three Ngati Awa men whose character, mana and reputation were restored after they too "were arrested, tried and labelled as rebels".

Mokomoko wasn't mentioned. Instead four years later Governor-General, Dame Cath Tizard granted the pardon on the grounds that it was "just and expedient".

No mention was made of him not committing the crime.

And that's the rub still for Mr Biddle.

"That's what we're fighting against now, it shouldn't be just an ordinary pardon."

The chief's bones were repatriated from Mt Eden Prison in 1988 and reburied beyond the marae. It's a high spot above flat fields that give way first to the sea and then to White Island on the horizon.

The current bill is unlike any other piece of legislation passed before in New Zealand. That's acknowledged by the committee chairman, Tau Henare, who told the descendants there was still time for changes to be made before its final passage into law.

"I don't think I'm getting ahead of myself ... but what you want you'll most probably get. I have a funny feeling that we may break a few rules on the way.

"To put it into context ... it has ramifications outside of our own country and I think we should get it as right as possible.

"This is about not only the Crown taking responsibility for its actions but acknowledging and trying to restore what was taken away."

It is important that the bill is struck in te reo Maori for the Te Whanau a Mokomoko Leadership Group, and there is still work to be done on the preamble.

The group wants it to reflect the whole history of what occurred and its ramifications.

In September 1865 a Crown force of 500 men arrived in the settlement to arrest Mokomoko and others the Crown thought to be responsible for the death.

Historians from the Office of Treaty settlements write: "The Crown force was involved in skirmishes with Te Whakatohea and other tribes in which people were killed, livestock seized and property destroyed. Mokomoko surrendered in October 1865 to stop the persecution of his people, but he maintained he was not one of those responsible for the earlier killings.

"The Crown considered that Te Whakatohea and other Bay of Plenty tribes had been in rebellion and, in 1866, confiscated approximately 448,000 acres [181,300ha]. It appears that Te Whakatohea had interests in over 100,000 acres of this land."

Karen Mokomoko was young when the bones were bought home. She told the committee, "We were run off our land and had to hide and treated like dogs."

Outside, Ms Mokomoko said dealing with the Government over the issue in the past few years had been easier because attitudes had softened.

"They seem to understand our mamae [hurt] and they seem to identify with our history ... and they're willing to support us."

Who is Carl Volkner to the wider whanau?

Mr Biddle says there isn't a question that the German missionary went bravely to his death.

"It was done by [Pai Marire missionary] Kereopa [Te Rau]. You always get a rebel and I can't tar [Pai Marire followers] with the same brush."

But the government of the day, he believes, is equally culpable because the tragedy was linked to the work (Tau Henare called it spying) that the missionary undertook on its behalf.

"All they were interested in was getting the economic base and getting the land for the colonists who were queuing up to come to New Zealand."

The group would like to meet other Te Whakatohea hapu and neighbouring tribes who he believes benefited from Mokomoko's demise through land acquisitions.

It is unfair to name them, Mr Biddle says, but he also wants to meet those who still unfairly blame Mokomoko for the confiscations. It is something that will have to be broached sensitively.

"So long as we can acknowledge and respect one another's korero we can move on. We have to be humble about it.

"It's how you put the truth. You don't put the truth to belittle anyone ... who are we to judge and who are we to condemn?"

"That way we can heal. I think Mokomoko would be happy."

The killing

On March 2, 1865, German missionary Reverend Carl Sylvius Volkner was slain at Opotiki. He was hung from a willow tree by his own congregation near the church Te Whakatohea had built for him.

The Church Missionary Society priest had lived among Te Whakatohea since 1861 in a period of complex intertribal politics against the background of the land wars. Letters indicate he was an informer for Governor George Grey.

Volkner, who had been in Auckland in January 1865, ignored warnings to stay away from Opotiki. He arrived on March 1 and was killed the next day, after praying and shaking hands with his killers.

He was decapitated and his blood tasted. Kereopa Te Rau, a follower of the Pai Marire religion (known to the British at the time as Hauhau from their warcry) forced out the eyes and swallowed them.

Te Whakatohea chief Mokomoko denied responsibility for the killing, claiming he was present neither when the decision was made to kill Volkner nor at the slaying.

However, witnesses at his trial in Auckland claimed Mokomoko was in the procession and carried the rope.